Insulin-induced lipohypertrophy: clinical and ultrasound characteristics

Background : Lipohypertrophy is primary dermal complication of insulin therapy. The data on the prevalence of lipohypertrophy in diabetic subjects are inconsistent, that may be due to the lack of sensitivity and subjectivity of palpation as diagnostic technique. Meanwhile, the reliability of lipohypertrophy detection can be increased by ultrasound. Aims : to compare clinical and ultrasound characteristics and to determine the risk factors of insulin-induced lipohypertrophy in diabetic subjects. Materials and methods : We observed 82 patients, including 26 individuals with type 1 diabetes and 56 subjects with type 2 diabetes. Duration of insulin therapy varied from 3 months to 37 years (median 14 years). The sites of insulin injections were assessed by palpation and ultrasound. Visualization protocol included gray-scale densitometry, strain elastography, and 3D Doppler power ultrasound. Scaled evaluation of ultrasound sings was applied. Insulin injection technique was assessed by questionnaire. Serum levels of insulin antibodies were determined by ELISA. Results : Lipohypertrophy was revealed by palpation and ultrasound in 57 and 80 patients (70% and 98%) respectively. Total lipohypertrophy area, acoustic density and total ultrasound score showed weak positive correlations with daily insulin dose (r=0.3, r=0.3 and r=0.35, respectively, all p<0.006). Patients receiving insulin analogues had smaller area of abdominal lipohypertrophy than those on human insulin (p=0.03). A positive correlation was found between abdominal lipohypertrophy area and mean postprandial glucose (r=0.35, p=0.001). A rare needle change and injections in lipohypertrophy sites were the most common deviations in insulin injection technique (70 and 47 subjects, 85% and 53% respectively). The levels of insulin antibodies showed no association with lipohypertrophy parameters. Conclusions : Patients with type 1 and type 2 diabetes demonstrate high prevalence of lipohypertrophy in insulin injection sites. Ultrasonography is more sensitive method of diagnostics of lipohypertrophy compared with palpation. Insulin-induced lipohypertrophy is associated with errors in injection technique and higher insulin doses.